Recovery of Rare Earth Elements Minerals

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Processing and Extractive Metallurgy".

Deadline for manuscript submissions: closed (31 July 2022) | Viewed by 14903

Special Issue Editors


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Guest Editor
Sustainable Minerals Processing, Future Industries Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA 5095, Australia
Interests: battery metals and critical minerals; rare earth elements; extractive metallurgy; mineral processing; process plant design and optimization
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Guest Editor
School of Resources and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China
Interests: complex sulfide ore; rare metals; rare earth; mineral processing; salt-lake resources

Special Issue Information

Dear Colleagues,

We are happy to announce that a Special Issue of the Minerals Journal which is focused on “Recovery of Rare Earth Elements Minerals” will be published in 2022. This Special Issue aims to showcase recent advances and innovative attempts geared toward processing of different ores and alternative/secondary resources to achieve enhanced rare earth element mineral recovery. The Minerals journal thus welcomes specific contributions related to various aspects on the beneficiation of rare earth element minerals, including the following:

  • Advanced processing of rare earth element minerals including (but not limited to) physical preconcentration strategies such as desliming, magnetic, gravity, and electrostatic separation;
  • Innovative froth flotation methods for rare earth element mineral recovery;
  • Hydrometallurgical and pyrometallurgical processing of rare earth element minerals;
  • Recent advances in the processing of secondary or unconventional resources for rare earth element mineral beneficiation;
  • New technological developments for rare earth element mineral recovery.

Dr. George Blankson Abaka-Wood
Prof. Dr. Xianping Luo
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • complex ores
  • leaching
  • rare earth elements
  • mineral processing
  • flotation
  • magnetic separation
  • gravity separation
  • ion adsorption clay
  • secondary resources

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Published Papers (5 papers)

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Research

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18 pages, 10941 KiB  
Article
Recovery of Rare Earth Elements Minerals in Complex Low-Grade Saprolite Ore by Froth Flotation
by George Blankson Abaka-Wood, Bob Johnson, Jonas Addai-Mensah and William Skinner
Minerals 2022, 12(9), 1138; https://doi.org/10.3390/min12091138 - 08 Sep 2022
Cited by 5 | Viewed by 2027
Abstract
This study presented the first in a series of investigations currently underway to develop efficacious, cost-effective, and benign processing opportunities to produce rare earth elements (REE)–rich concentrate from an Australian complex low–grade saprolite ore [1.14% total rare earth oxides (TREO) grade], which is [...] Read more.
This study presented the first in a series of investigations currently underway to develop efficacious, cost-effective, and benign processing opportunities to produce rare earth elements (REE)–rich concentrate from an Australian complex low–grade saprolite ore [1.14% total rare earth oxides (TREO) grade], which is primarily exploited for its gold and copper values. This work specifically presented a preliminary flotation investigation carried out on the ore using sodium oleate as a collector. The relative effects of pulp pH, desliming, and depressants were investigated to ascertain any chance of recovering and upgrading REE minerals in saprolite ore using three different processing configurations. Based on the experimental results, flotation processes carried out on raw feed allowed the recovery of the majority of REE minerals (>50%), but the process was unselective, where clay and silicate gangue minerals reported into the flotation concentrate along with the REE minerals. However, desliming before flotation in the presence of depressants (starch and sodium silicate) improved REE minerals flotation selectivity, which produced concentrates assaying 5.87% and 4.22% TREO grades, with corresponding recoveries of 45% and 50% at pulp pH 9 and 10.5, respectively. Mineralogical analysis conducted on selected flotation concentrate indicated that silicate and clay gauge minerals were recovered via the synergistic act of surface activation and entrainment due to their fine to ultrafine nature. A comparison of all the test results revealed a haphazard grade–recovery relationship suggesting that there is an opportunity to further maximize both REE recovery and grade through further flotation studies where other process parameters may be investigated and optimized. The prospect of using magnetic separation has also been suggested. Full article
(This article belongs to the Special Issue Recovery of Rare Earth Elements Minerals)
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14 pages, 2934 KiB  
Article
Bioadsorption of Terbium(III) by Spores of Bacillus subtilis
by Wei Dong, Huimin Wang, Zhoushen Ning, Kaijian Hu and Xianping Luo
Minerals 2022, 12(7), 866; https://doi.org/10.3390/min12070866 - 08 Jul 2022
Cited by 3 | Viewed by 1566
Abstract
Wastewater containing low concentrations of rare earth ions not only constitutes a waste of rare earth resources but also threatens the surrounding environment. It is therefore necessary to develop environmentally friendly methods of recovering rare earth ions. The spores produced by Bacillus are [...] Read more.
Wastewater containing low concentrations of rare earth ions not only constitutes a waste of rare earth resources but also threatens the surrounding environment. It is therefore necessary to develop environmentally friendly methods of recovering rare earth ions. The spores produced by Bacillus are resistant to extreme environments and are effective in the bioadsorption of rare earth ions, but their adsorption behaviors and mechanisms are not well understood. In this study, the cells and spores of Bacillus subtilis PS533 and PS4150 were used as biosorbents, and their adsorption of terbium ions was compared under different conditions. The adsorption characteristics of the spores were investigated, as were the possible mechanisms of interaction between the spores and rare earth ions. The results showed that the PS4150 spores had the best adsorption effect on Tb(III), with the removal percentage reaching 95.2%. Based on a computational simulation, SEM observation, XRD, XPS, and FTIR analyses, it was suggested that the adsorption of Tb(III) by the spores conforms to the pseudo−second−order kinetics and the Langmuir adsorption isotherm model. This indicates that the adsorption process mainly consists of chemical adsorption, and that groups such as amino, hydroxyl, methyl, and phosphate, which are found on the surface of the spores, are involved in the bioadsorption process. All of these findings suggest that Bacillus subtilis spores can be used as a potential biosorbent for the recovery of rare earth ions from wastewater. Full article
(This article belongs to the Special Issue Recovery of Rare Earth Elements Minerals)
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29 pages, 4716 KiB  
Article
Influence of P and Ti on Phase Formation at Solidification of Synthetic Slag Containing Li, Zr, La, and Ta
by Thomas Schirmer, Hao Qiu, Daniel Goldmann, Christin Stallmeister and Bernd Friedrich
Minerals 2022, 12(3), 310; https://doi.org/10.3390/min12030310 - 28 Feb 2022
Cited by 5 | Viewed by 1987
Abstract
In the future, it will become increasingly important to recover critical elements from waste materials. For many of these elements, purely mechanical processing is not efficient enough. An already established method is pyrometallurgical processing, with which many of the technologically important elements, such [...] Read more.
In the future, it will become increasingly important to recover critical elements from waste materials. For many of these elements, purely mechanical processing is not efficient enough. An already established method is pyrometallurgical processing, with which many of the technologically important elements, such as Cu or Co, can be recovered in the metal phase. Ignoble elements, such as Li, are known to be found in the slag. Even relatively base or highly redox-sensitive elements, such as Zr, REEs, or Ta, can be expected to accumulate in the slag. In this manuscript, the methods for determining the phase formation and the incorporation of these elements were developed and optimized, and the obtained results are discussed. For this purpose, oxide slags were synthesized with Al, Si, Ca, and the additives, P and Ti. To this synthetic slag were added the elements, Zr and La (which can be considered proxies for the light REEs), as well as Ta. On the basis of the obtained results, it can be concluded that Ti or P can have strong influences on the phase formation. In the presence of Ti, La, and Ta, predominantly scavenged by perovskite (Ca1−wLa2/3wTi1−(x+y+z)Al4/3xZryTa4/5zO3), and Zr predominantly as zirconate (Ca1−wLa2/3wZr4−(x+y+z)Al4/3xTiyTa4/5zO9), with the P having no effect on this behavior. Without Ti, the Zr and Ta are incorporated into the pyrochlore (La2−xCa3/2x−yZr2+2/4y−zTa4/5zO7), regardless of the presence of phosphorus. In addition to pyrochlore, La accumulates primarily in britholite-type La oxy- or phosphosilicates. Without P and Ti, similar behavior is observed, except that the britholite-like La silicates do not contain P, and the scavenging of La is less efficient. Lithium, on the other hand, forms its own compounds, such as LiAlO2(Si), LiAl5O8, eucryptite, and Li silicate. Additionally, in the presence of P, Li3PO4 is formed, and the eucryptite incorporates P, which indicates an additional P-rich eutectic melt. Full article
(This article belongs to the Special Issue Recovery of Rare Earth Elements Minerals)
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15 pages, 2511 KiB  
Article
A Hybrid Experimental and Theoretical Approach to Optimize Recovery of Rare Earth Elements from Acid Mine Drainage Precipitates by Oxalic Acid Precipitation
by Yan Wang, Paul Ziemkiewicz and Aaron Noble
Minerals 2022, 12(2), 236; https://doi.org/10.3390/min12020236 - 12 Feb 2022
Cited by 7 | Viewed by 2611
Abstract
The development of processing techniques for the extraction of rare earth elements and critical minerals (REE/CM) from acid mine drainage precipitates (AMDp) has attracted increased interest in recent years. Processes under development often utilize a standard hydrometallurgical approach that includes leaching and solvent [...] Read more.
The development of processing techniques for the extraction of rare earth elements and critical minerals (REE/CM) from acid mine drainage precipitates (AMDp) has attracted increased interest in recent years. Processes under development often utilize a standard hydrometallurgical approach that includes leaching and solvent extraction followed by oxalic acid precipitation and calcination to produce a final rare earth oxide product. Impurities such as Ca, Al, Mn, Fe and Mg can be detrimental in the oxalate precipitation step and a survey of the literature showed limited data pertaining to the REE precipitation efficiency in solutions with high impurity concentrations. As such, a systematic laboratory-scale precipitation study was performed on a strip solution generated by the acid leaching and solvent extraction of an AMDp feedstock to identify the optimal processing conditions that maximize REE precipitation efficiency and product purity while minimizing the oxalic acid dosage. Given the unique chemical characteristics of AMDp, the feed solution utilized in this study contained a moderate concentration of REEs (440 mg/L) as well a significant concentration (>7000 mg/L total) of non-REE contaminants such as Ca, Al, Mn, Fe and Mg. Initially, a theoretical basis for the required oxalic acid dose, optimal pH and predicted precipitation efficiency was established by solution equilibrium calculations. Following the solution chemistry calculations, bench-scale precipitation experiments were conducted and these test results indicate that a pH of 1.5 to 2, a reaction time of more than 2 h and an oxalic acid dosage of 30 to 40 g/L optimized the REEs recovery of at ~95% to nearly 100% for individual REE species. The test results validated the optimal pH predicted by the solution chemistry calculations (1.5 to 5); however, the predicted dosage needed for complete REE recovery (10 g/L) was significantly lower than the experimentally-determined dosage of 30 to 40 g/L. The reason for this discrepancy was determined to be due to the large concentration of impurities and large number of potential metal complexes that cause inaccuracies in the solution equilibrium calculations. Based on these findings, a hybrid experimental and theoretical approach is proposed for future oxalic acid precipitation optimization studies. Full article
(This article belongs to the Special Issue Recovery of Rare Earth Elements Minerals)
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Review

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33 pages, 4834 KiB  
Review
Review on the Development and Utilization of Ionic Rare Earth Ore
by Xianping Luo, Yongbing Zhang, Hepeng Zhou, Kunzhong He, Caigui Luo, Zishuai Liu and Xuekun Tang
Minerals 2022, 12(5), 554; https://doi.org/10.3390/min12050554 - 28 Apr 2022
Cited by 31 | Viewed by 5364
Abstract
Rare earth, with the reputation of “industrial vitamins”, has become a strategic key metal for industrial powers with increasingly significant industrial application value. As a unique rare earth resource, ionic rare earth ore (IREO) has the outstanding advantages of complete composition, rich resource [...] Read more.
Rare earth, with the reputation of “industrial vitamins”, has become a strategic key metal for industrial powers with increasingly significant industrial application value. As a unique rare earth resource, ionic rare earth ore (IREO) has the outstanding advantages of complete composition, rich resource reserves, low radioactivity, and high comprehensive utilization value. IREO is the main source of medium and heavy rare earth raw materials, which are in great demand all over the world. Since the discovery of IREO, it has attracted extensive attention. Scientists in China and the around world have carried out a lot of research and practical work and achieved a series of important breakthroughs. This paper introduces the discovery process, metallogenic causes, deposit characteristics, and the prospecting research progress of IREO, so as to deepen the understanding of the global distribution of ionic rare earth resources and the prospecting direction of ionic rare earth deposits. The leaching principle of IREO, the innovation of leaching process, the influencing factors and technological development of in situ leaching process, and the technical adaptability of in situ leaching process are reviewed. The development of leachate purification and rare earth extraction technology is summarized. We aim to provide guidance for the industrial development of IREO through the above review analysis. Additionally, the problems existing in the development of IREO are pointed out from the aspects of technology, economy, and the environment. Ultimately, a series of suggestions are put forward, such as the development of ammonium free extraction technology in the whole exploitation process of in situ leaching and leachate purification and rare earth precipitation, research on enhancing of seepage and mass transfer process, and research on the development of new technologies for impurity removal of leachate and extraction of rare earth, so as to promote the development of green and efficient exploitation new technologies and sustainable development of ionic rare earth ore. Full article
(This article belongs to the Special Issue Recovery of Rare Earth Elements Minerals)
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